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Parikh SJ, Edara S, Deodhar S, Singh AK, Maekawa K, Zhang Q, Glass KC, Shah MB. Structural and biophysical analysis of cytochrome P450 2C9*14 and *27 variants in complex with losartan. J Inorg Biochem 2024; 258:112622. [PMID: 38852293 PMCID: PMC11285081 DOI: 10.1016/j.jinorgbio.2024.112622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 05/20/2024] [Accepted: 05/26/2024] [Indexed: 06/11/2024]
Abstract
The human cytochrome P450 (CYP) 1, 2 and 3 families of enzymes are responsible for the biotransformation of a majority of the currently available pharmaceutical drugs. The highly polymorphic CYP2C9 predominantly metabolizes many drugs including anticoagulant S-warfarin, anti-hypertensive losartan, anti-diabetic tolbutamide, analgesic ibuprofen, etc. There are >80 single nucleotide changes identified in CYP2C9, many of which significantly alter the clearance of important drugs. Here we report the structural and biophysical analysis of two polymorphic variants, CYP2C9*14 (Arg125His) and CYP2C9*27 (Arg150Leu) complexed with losartan. The X-ray crystal structures of the CYP2C9*14 and *27 illustrate the binding of two losartan molecules, one in the active site near heme and another on the periphery. Both losartan molecules are bound in an identical conformation to that observed in the previously solved CYP2C9 wild-type complex, however, the number of losartan differs from the wild-type structure, which showed binding of three molecules. Additionally, isothermal titration calorimetry experiments reveal a lower binding affinity of losartan with *14 and *27 variants when compared to the wild-type. Overall, the results provide new insights into the effects of these genetic polymorphisms and suggests a possible mechanism contributing to reduced metabolic activity in patients carrying these alleles.
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Affiliation(s)
- Sonia J Parikh
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA
| | - Sreeja Edara
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA
| | - Shruti Deodhar
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA
| | - Ajit K Singh
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Keiko Maekawa
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto 610-0395, Japan
| | - Qinghai Zhang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Karen C Glass
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Manish B Shah
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA.
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2
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Barata IS, Rueff J, Kranendonk M, Esteves F. Pleiotropy of Progesterone Receptor Membrane Component 1 in Modulation of Cytochrome P450 Activity. J Xenobiot 2024; 14:575-603. [PMID: 38804287 PMCID: PMC11130977 DOI: 10.3390/jox14020034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
Progesterone receptor membrane component 1 (PGRMC1) is one of few proteins that have been recently described as direct modulators of the activity of human cytochrome P450 enzymes (CYP)s. These enzymes form a superfamily of membrane-bound hemoproteins that metabolize a wide variety of physiological, dietary, environmental, and pharmacological compounds. Modulation of CYP activity impacts the detoxification of xenobiotics as well as endogenous pathways such as steroid and fatty acid metabolism, thus playing a central role in homeostasis. This review is focused on nine main topics that include the most relevant aspects of past and current PGRMC1 research, focusing on its role in CYP-mediated drug metabolism. Firstly, a general overview of the main aspects of xenobiotic metabolism is presented (I), followed by an overview of the role of the CYP enzymatic complex (IIa), a section on human disorders associated with defects in CYP enzyme complex activity (IIb), and a brief account of cytochrome b5 (cyt b5)'s effect on CYP activity (IIc). Subsequently, we present a background overview of the history of the molecular characterization of PGRMC1 (III), regarding its structure, expression, and intracellular location (IIIa), and its heme-binding capability and dimerization (IIIb). The next section reflects the different effects PGRMC1 may have on CYP activity (IV), presenting a description of studies on the direct effects on CYP activity (IVa), and a summary of pathways in which PGRMC1's involvement may indirectly affect CYP activity (IVb). The last section of the review is focused on the current challenges of research on the effect of PGRMC1 on CYP activity (V), presenting some future perspectives of research in the field (VI).
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Affiliation(s)
- Isabel S. Barata
- Department of Pediatrics, Division of Endocrinology, Diabetology and Metabolism, University Children’s Hospital, University of Bern, 3010 Bern, Switzerland;
- Translational Hormone Research Program, Department of Biomedical Research, University of Bern, 3010 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - José Rueff
- ToxOmics, NOVA Medical School, Faculdade de Ciências Médicas, NMS|FCM, Universidade NOVA de Lisboa, Campo Mártires da Pátria 130, 1169-056 Lisboa, Portugal;
| | - Michel Kranendonk
- ToxOmics, NOVA Medical School, Faculdade de Ciências Médicas, NMS|FCM, Universidade NOVA de Lisboa, Campo Mártires da Pátria 130, 1169-056 Lisboa, Portugal;
| | - Francisco Esteves
- ToxOmics, NOVA Medical School, Faculdade de Ciências Médicas, NMS|FCM, Universidade NOVA de Lisboa, Campo Mártires da Pátria 130, 1169-056 Lisboa, Portugal;
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Salazar YEAR, Louzada J, Puça MCSDB, Guimarães LFF, Vieira JLF, de Siqueira AM, Gil JP, de Brito CFA, de Sousa TN. Delayed gametocyte clearance in Plasmodium vivax malaria is associated with polymorphisms in the cytochrome P450 reductase (CPR). Antimicrob Agents Chemother 2024; 68:e0120423. [PMID: 38411047 PMCID: PMC10989009 DOI: 10.1128/aac.01204-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/31/2024] [Indexed: 02/28/2024] Open
Abstract
Primaquine (PQ) is the main drug used to eliminate dormant liver stages and prevent relapses in Plasmodium vivax malaria. It also has an effect on the gametocytes of Plasmodium falciparum; however, it is unclear to what extent PQ affects P. vivax gametocytes. PQ metabolism involves multiple enzymes, including the highly polymorphic CYP2D6 and the cytochrome P450 reductase (CPR). Since genetic variability can impact drug metabolism, we conducted an evaluation of the effect of CYP2D6 and CPR variants on PQ gametocytocidal activity in 100 subjects with P. vivax malaria. To determine gametocyte density, we measured the levels of pvs25 transcripts in samples taken before treatment (D0) and 72 hours after treatment (D3). Generalized estimating equations (GEEs) were used to examine the effects of enzyme variants on gametocyte densities, adjusting for potential confounding factors. Linear regression models were adjusted to explore the predictors of PQ blood levels measured on D3. Individuals with the CPR mutation showed a smaller decrease in gametocyte transcript levels on D3 compared to those without the mutation (P = 0.02, by GEE). Consistent with this, higher PQ blood levels on D3 were associated with a lower reduction in pvs25 transcripts. Based on our findings, the CPR variant plays a role in the persistence of gametocyte density in P. vivax malaria. Conceptually, our work points to pharmacogenetics as a non-negligible factor to define potential host reservoirs with the propensity to contribute to transmission in the first days of CQ-PQ treatment, particularly in settings and seasons of high Anopheles human-biting rates.
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Affiliation(s)
- Yanka Evellyn Alves Rodrigues Salazar
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Jaime Louzada
- Universidade Federal de Roraima, Boa Vista, Roraima, Brazil
| | - Maria Carolina Silva de Barros Puça
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Luiz Felipe Ferreira Guimarães
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | | | - André Machado de Siqueira
- Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - José Pedro Gil
- Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Solna, Sweden
| | - Cristiana Ferreira Alves de Brito
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
| | - Tais Nobrega de Sousa
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Minas Gerais, Brazil
- Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Solna, Sweden
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Tateishi Y, Webb SN, Li B, Liu L, Lindsey Rose K, Leser M, Patel P, Guengerich FP. Proteomics, modeling, and fluorescence assays delineate cytochrome b 5 residues involved in binding and stimulation of cytochrome P450 17A1 17,20-lyase. J Biol Chem 2024; 300:105688. [PMID: 38280431 PMCID: PMC10878793 DOI: 10.1016/j.jbc.2024.105688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 01/29/2024] Open
Abstract
Cytochrome b5 (b5) is known to stimulate some catalytic activities of cytochrome P450 (P450, CYP) enzymes, although mechanisms still need to be defined. The reactions most strongly enhanced by b5 are the 17,20-lyase reactions of P450 17A1 involved in steroid biosynthesis. We had previously used a fluorescently labeled human b5 variant (Alexa 488-T70C-b5) to characterize human P450 17A1-b5 interactions, but subsequent proteomic analyses indicated that lysines in b5 were also modified with Alexa 488 maleimide in addition to Cys-70, due to disulfide dimerization of the T70C mutant. A series of b5 variants were constructed with Cys replacements for the identified lysine residues and labeled with the dye. Fluorescence attenuation and the function of b5 in the steroid lyase reaction depended on the modified position. Apo-b5 (devoid of heme group) studies revealed the lack of involvement of the b5 heme in the fluorescence attenuation. A structural model of b5 with P450 17A1 was predicted using AlphaFold-Multimer algorithms/Rosetta docking, based upon the individual structures, which predicted several new contacts not previously reported, that is, interactions of b5 Glu-48:17A1 Arg-347, b5 Glu-49:17A1 Arg-449, b5 Asp-65:17A1 Arg-126, b5 Asp-65:17A1 Arg-125, and b5 Glu-61:17A1 Lys-91. Fluorescence polarization assays with two modified b5 variants yielded Kd values (for b5-P450 17A1) of 120 to 380 nM, the best estimate of binding affinity. We conclude that both monomeric and dimeric b5 can bind to P450 17A1 and stimulate activity. Results with the mutants indicate that several Lys residues in b5 are sensitive to the interaction with P450 17A1, including Lys-88 and Lys-91.
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Affiliation(s)
- Yasuhiro Tateishi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Stephany N Webb
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Bian Li
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Lu Liu
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Kristie Lindsey Rose
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Proteomics Laboratory, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Micheal Leser
- Proteomics Laboratory, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Purvi Patel
- Proteomics Laboratory, Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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5
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Hassan AA, Abdelgayed SS, Mansour SZ. Liver and ovarian toxicities boosted by bisphenol and gamma radiation in female albino rats. Hum Exp Toxicol 2024; 43:9603271231219264. [PMID: 38263794 DOI: 10.1177/09603271231219264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Bisphenol A (BPA), a carbon-based synthetic polymer compound, was newly classified as an environmental toxicant and an endocrine-disrupting chemical leading to abnormalities in cell proliferation, apoptosis, or migration that contributes to cancer development and progression. This study aims to evaluate the effect of the elevation of γ- radiation dose and BPA on the liver and ovaries of female rats. In this study, eighty female albino rats (130-150 g) were used in this work. Rats in this experiment received BPA in ethanol (50 mg/kg b. wt.) for 30 days, day after day, and in the irradiated groups, animals were administered BPA and then exposed to γ- radiation in doses (2, 4, and 6 Gy) one shot dose. Several members of the cytochrome family were examined. Exposure to γ-radiation and BPA showed an increase in cytochrome P450 and b5 fold change. Further, BPA and γ-radiation activate α and β estrogen receptors and also downregulate aromatase (CYT19) fold change. The current results also revealed that BPA and/or γ-radiation regulate the protein expression of the PI3K/Akt signaling pathway. The steroidogenic acute regulatory protein (StAR) appeared to be targeted by BPA and γ-radiation and its relative expression was elevated significantly by raising the γ-radiation dose. In conclusion, exposure to BPA, an endocrine-disrupting chemical, leads to marked toxicity. Additionally, toxicity is heightened by increasing the γ-radiation dose, either alone or in combination with BPA.
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Affiliation(s)
- Asmaa A Hassan
- Radiation Biology Department, National Centre for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt
| | - Sherein S Abdelgayed
- Pathology Department, Faculty of Veterinary Medicine, Cairo University, Cairo, Egypt
| | - Somaya Z Mansour
- Radiation Biology Department, National Centre for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt
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6
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Sahoo BR, Ramamoorthy A. Direct interaction between the transmembrane helices stabilize cytochrome P450 2B4 and cytochrome b5 redox complex. Biophys Chem 2023; 301:107092. [PMID: 37586236 PMCID: PMC10838600 DOI: 10.1016/j.bpc.2023.107092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/18/2023]
Abstract
The catalytic activity of cytochrome P450 2B4 (CYP2B4) is moderated by its cognate redox partner cytochrome b5 (Cyt-b5). The endoplasmic reticulum (ER) membrane and intermolecular transmembrane (TM) interaction between CYP2B4 and Cyt-b5 regulate the substrate catalysis and the reaction rate. This emphasizes the significance of elucidating the molecular basis of CYP2B4 and Cyt-b5 complexation in a membrane environment to better understand the enzymatic activity of CYP2B4. Our previous solid-state NMR studies revealed the membrane topology of the transmembrane domains of these proteins in the free and complex forms. Here, we show the cross-angle complex formation by the single-pass TM domains of CYP2B4 and Cyt-b5, which is mainly driven by several salt-bridges (E2-R128, R21-D104 and K25-D104), using a multi-microsecond molecular dynamic simulation. Additionally, the leucine-zipper residues (L8, L12, L15, L18 and L19 from CYP2B4) and π-stacking between H23 and F20 residues of CYP2B4 and W110 of Cyt-b5 are identified to stabilize the TM-TM complex in the ER membrane. The simulated tilts of the helices in the free and in the complex are in excellent agreement with solid-state NMR results. The TM-TM packing influences a higher order structural stability when compared to the complex formed by the truncated soluble domains of these two proteins. MM/PBSA based binding free energy estimates nearly 100-fold higher binding affinity (ΔG = -2810.68 ± 696.44 kJ/mol) between the soluble domains of the full-length CYP2B4 and Cyt-b5 when embedded in lipid membrane as compared to the TM-domain-truncated soluble domains (ΔG = -27.406 ± 10.32 kJ/mol). The high-resolution full-length CYP2B4-Cyt-b5 complex structure and its dynamics in a native ER membrane environment reported here could aid in the development of approaches to effectively modulate the drug-metabolism activity of CYP2B4.
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Affiliation(s)
- Bikash R Sahoo
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
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7
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Richard AM, Wong NR, Harris K, Sundar R, Scott EE, Pochapsky TC. Selective steroidogenic cytochrome P450 haem iron ligation by steroid-derived isonitriles. Commun Chem 2023; 6:183. [PMID: 37660137 PMCID: PMC10475101 DOI: 10.1038/s42004-023-00994-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 08/23/2023] [Indexed: 09/04/2023] Open
Abstract
Alkyl isonitriles, R-NC, have previously been shown to ligate the heme (haem) iron of cytochromes P450 in both accessible oxidation states (ferrous, Fe2+, and ferric, Fe3+). Herein, the preparation of four steroid-derived isonitriles and their interactions with several P450s, including the steroidogenic CYP17A1 and CYP106A2, as well as the more promiscuous drug metabolizers CYP3A4 and CYP2D6, is described. It was found that successful ligation of the heme iron by the isonitrile functionality for a given P450 depends on both the position and stereochemistry of the isonitrile on the steroid skeleton. Spectral studies indicate that isonitrile ligation of the ferric heme is stable upon reduction to the ferrous form, with reoxidation resulting in the original complex. A crystallographic structure of CYP17A1 with an isonitrile derived from pregnanalone further confirmed the interaction and identified the absolute stereochemistry of the bound species.
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Affiliation(s)
- Alaina M Richard
- Chemical Biology Program, University of Michigan, Ann Arbor, 48109, MI, USA
| | - Nathan R Wong
- Dept. of Biochemistry, Brandeis University, 415 South St., Waltham, 02454-9110, MA, USA
| | - Kurt Harris
- Department of Medicinal Chemistry, University of Michigan, 428 Church St., Ann Arbor, 48109-1065, MI, USA
| | - Reethy Sundar
- Dept. of Biochemistry, Brandeis University, 415 South St., Waltham, 02454-9110, MA, USA
| | - Emily E Scott
- Chemical Biology Program, University of Michigan, Ann Arbor, 48109, MI, USA
- Department of Medicinal Chemistry, University of Michigan, 428 Church St., Ann Arbor, 48109-1065, MI, USA
- Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, 48109, MI, USA
| | - Thomas C Pochapsky
- Dept. of Biochemistry, Brandeis University, 415 South St., Waltham, 02454-9110, MA, USA.
- Dept. of Chemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, 415 South St, Waltham, 02454-9110, MA, USA.
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8
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Burris-Hiday SD, Scott EE. Allosteric modulation of cytochrome P450 enzymes by the NADPH cytochrome P450 reductase FMN-containing domain. J Biol Chem 2023; 299:105112. [PMID: 37517692 PMCID: PMC10481364 DOI: 10.1016/j.jbc.2023.105112] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/01/2023] Open
Abstract
NADPH-cytochrome P450 reductase delivers electrons required by heme oxygenase, squalene monooxygenase, fatty acid desaturase, and 48 human cytochrome P450 enzymes. While conformational changes supporting reductase intramolecular electron transfer are well defined, intermolecular interactions with these targets are poorly understood, in part because of their transient association. Herein the reductase FMN domain responsible for interacting with targets was fused to the N-terminus of three drug-metabolizing and two steroidogenic cytochrome P450 enzymes to increase the probability of interaction. These artificial fusion enzymes were profiled for their ability to bind their respective substrates and inhibitors and to perform catalysis supported by cumene hydroperoxide. Comparisons with the isolated P450 enzymes revealed that even the oxidized FMN domain causes substantial and diverse effects on P450 function. The FMN domain could increase, decrease, or not affect total ligand binding and/or dissociation constants depending on both P450 enzyme and ligand. As examples, FMN domain fusion has no effect on inhibitor ketoconazole binding to CYP17A1 but substantially altered CYP21A2 binding of the same compound. FMN domain fusion to CYP21A2 resulted in differential effects dependent on whether the ligand was 17α-hydroxyprogesterone versus ketoconazole. Similar enzyme-specific effects were observed on steady-state kinetics. These observations are most consistent with FMN domain interacting with the proximal P450 surface to allosterically impact P450 ligand binding and metabolism separate from electron delivery. The variety of effects on different P450 enzymes and on the same P450 with different ligands suggests intricate and differential allosteric communication between the P450 active site and its proximal reductase-binding surface.
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Affiliation(s)
- Sarah D Burris-Hiday
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Emily E Scott
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA; Departments of Pharmacology and Biological Chemistry and the Programs in Chemical Biology and Biophysics, University of Michigan, Ann Arbor, Michigan, USA.
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9
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Kumar A, Estrada DF. Structural basis of bidirectional allostery across the heme in a cytochrome P450 enzyme. J Biol Chem 2023; 299:104977. [PMID: 37390989 PMCID: PMC10416055 DOI: 10.1016/j.jbc.2023.104977] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/02/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023] Open
Abstract
Cytochromes P450 (CYPs) are heme-containing enzymes that are present in all kingdoms of life and share a structurally homologous, globular protein fold. CYPs utilize structures distal to the heme to recognize and coordinate substrates, while the necessary interactions with redox partner proteins are mediated at the opposite, proximal surface. In the current study, we investigated the functional allostery across the heme for the bacterial enzyme CYP121A1, which utilizes a non-polar distal-to-distal dimer interface for specific binding of its dicyclotyrosine substrate. Fluorine-detected Nuclear Magnetic Resonance (19F-NMR) spectroscopy was combined with site-specific labeling of a distal surface residue (S171C of the FG-loop), one residue of the B-helix (N84C), and two proximal surface residues (T103C and T333C) with a thiol-reactive fluorine label. Adrenodoxin was used as a substitute redox protein and was found to promote a closed arrangement of the FG-loop, similar to the addition of substrate alone. Disruption of the protein-protein interface by mutagenesis of two CYP121 basic surface residues removed the allosteric effect. Moreover, 19F-NMR spectra of the proximal surface indicate that ligand-induced allostery modulates the environment at the C-helix but not the meander region of the enzyme. In light of the high degree of structural homology in this family of enzymes, we interpret the findings from this work to represent a conserved allosteric network in CYPs.
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Affiliation(s)
- Amit Kumar
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo, New York, USA
| | - D Fernando Estrada
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo, New York, USA.
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10
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Angle ED, Cox PM. Multidisciplinary Insights into the Structure-Function Relationship of the CYP2B6 Active Site. Drug Metab Dispos 2023; 51:369-384. [PMID: 36418184 DOI: 10.1124/dmd.122.000853] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 10/12/2022] [Accepted: 11/04/2022] [Indexed: 11/27/2022] Open
Abstract
Cytochrome P450 2B6 (CYP2B6) is a highly polymorphic human enzyme involved in the metabolism of many clinically relevant drugs, environmental toxins, and endogenous molecules with disparate structures. Over the last 20-plus years, in silico and in vitro studies of CYP2B6 using various ligands have provided foundational information regarding the substrate specificity and structure-function relationship of this enzyme. Approaches such as homology modeling, X-ray crystallography, molecular docking, and kinetic activity assays coupled with CYP2B6 mutagenesis have done much to characterize this originally neglected monooxygenase. However, a complete understanding of the structural details that make new chemical entities substrates of CYP2B6 is still lacking. Surprisingly little in vitro data has been obtained about the structure-function relationship of amino acids identified to be in the CYP2B6 active site. Since much attention has already been devoted to elucidating the function of CYP2B6 allelic variants, here we review the salient findings of in silico and in vitro studies of the CYP2B6 structure-function relationship with a deliberate focus on the active site. In addition to summarizing these complementary approaches to studying structure-function relationships, we note gaps/challenges in existing data such as the need for more CYP2B6 crystal structures, molecular docking results with various ligands, and data coupling CYP2B6 active site mutagenesis with kinetic parameter measurement under standard expression conditions. Harnessing in silico and in vitro techniques in tandem to understand the CYP2B6 structure-function relationship will likely offer further insights into CYP2B6-mediated metabolism. SIGNIFICANCE STATEMENT: The apparent importance of cytochrome P450 2B6 (CYP2B6) in the metabolism of various xenobiotics and endogenous molecules has grown since its discovery with many in silico and in vitro studies offering a partial description of its structure-function relationship. Determining the structure-function relationship of CYP2B6 is difficult but may be aided by thorough biochemical investigations of the CYP2B6 active site that provide a more complete pharmacological understanding of this important enzyme.
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Affiliation(s)
- Ethan D Angle
- Department of Biology and Chemistry, College of Liberal Arts and Sciences, Azusa Pacific University, Azusa, California (E.D.A., P.M.C.) and Roy J. and Lucille A. Carver College of Medicine University of Iowa, Iowa City, Iowa (E.D.A.)
| | - Philip M Cox
- Department of Biology and Chemistry, College of Liberal Arts and Sciences, Azusa Pacific University, Azusa, California (E.D.A., P.M.C.) and Roy J. and Lucille A. Carver College of Medicine University of Iowa, Iowa City, Iowa (E.D.A.)
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11
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Zhao X, Zhao Y, Gou M, Liu CJ. Tissue-preferential recruitment of electron transfer chains for cytochrome P450-catalyzed phenolic biosynthesis. SCIENCE ADVANCES 2023; 9:eade4389. [PMID: 36630494 PMCID: PMC9833660 DOI: 10.1126/sciadv.ade4389] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Cytochrome P450 system consists of P450 monooxygenase and redox pattern(s). While the importance of monooxygenases in plant metabolism is well documented, the metabolic roles of the related redox components have been largely overlooked. Here, we show that distinct electron transfer chains are recruited in phenylpropanoid-monolignol P450 systems to support the synthesis and distribution of different classes of phenolics in different plant tissues. While Arabidopsis cinnamate 4-hydroxylase adopts conventional NADPH-cytochrome P450 oxidoreductase (CPR) electron transfer chain for its para-hydroxylation reaction, ferulate 5-hydroxylase uses both NADPH-CPR-cytochrome b5 (CB5) and NADH-cytochrome b5 reductase-CB5 chains to support benzene ring 5-hydroxylation, in which the former route is primarily recruited in the stem for syringyl lignin synthesis, while the latter dominates in the syntheses of 5-hydroxylated phenolics in seeds and seed coat suberin. Our study unveils an additional layer of complexity and versatility of P450 system that the plants evolved for diversifying phenolic repertoires.
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12
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Roberts AG, Stevens JC, Szklarz GD, Scott EE, Kumar S, Shah MB, Halpert JR. Four Decades of Cytochrome P450 2B Research: From Protein Adducts to Protein Structures and Beyond. Drug Metab Dispos 2023; 51:111-122. [PMID: 36310033 PMCID: PMC11022898 DOI: 10.1124/dmd.122.001109] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/18/2022] [Accepted: 10/20/2022] [Indexed: 01/03/2023] Open
Abstract
This article features selected findings from the senior author and colleagues dating back to 1978 and covering approximately three-fourths of the 60 years since the discovery of cytochrome P450. Considering the vast number of P450 enzymes in this amazing superfamily and their importance for so many fields of science and medicine, including drug design and development, drug therapy, environmental health, and biotechnology, a comprehensive review of even a single topic is daunting. To make a meaningful contribution to the 50th anniversary of Drug Metabolism and Disposition, we trace the development of the research in a single P450 laboratory through the eyes of seven individuals with different backgrounds, perspectives, and subsequent career trajectories. All co-authors are united in their fascination for the structural basis of mammalian P450 substrate and inhibitor selectivity and using such information to improve drug design and therapy. An underlying theme is how technological advances enable scientific discoveries that were impossible and even inconceivable to prior generations. The work performed spans the continuum from: 1) purification of P450 enzymes from animal tissues to purification of expressed human P450 enzymes and their site-directed mutants from bacteria; 2) inhibition, metabolism, and spectral studies to isothermal titration calorimetry, deuterium exchange mass spectrometry, and NMR; 3) homology models based on bacterial P450 X-ray crystal structures to rabbit and human P450 structures in complex with a wide variety of ligands. Our hope is that humanizing the scientific endeavor will encourage new generations of scientists to make fundamental new discoveries in the P450 field. SIGNIFICANCE STATEMENT: The manuscript summarizes four decades of work from Dr. James Halpert's laboratory, whose investigations have shaped the cytochrome P450 field, and provides insightful perspectives of the co-authors. This work will also inspire future drug metabolism scientists to make critical new discoveries in the cytochrome P450 field.
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Affiliation(s)
- Arthur G Roberts
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.).
| | - Jeffrey C Stevens
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Grazyna D Szklarz
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Emily E Scott
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Santosh Kumar
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Manish B Shah
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - James R Halpert
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
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Liu CJ. Cytochrome b 5: A versatile electron carrier and regulator for plant metabolism. FRONTIERS IN PLANT SCIENCE 2022; 13:984174. [PMID: 36212330 PMCID: PMC9539407 DOI: 10.3389/fpls.2022.984174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
Cytochrome b 5 (CB5) is a small heme-binding protein, known as an electron donor delivering reducing power to the terminal enzymes involved in oxidative reactions. In plants, the CB5 protein family is substantially expanded both in its isoform numbers and cellular functions, compared to its yeast and mammalian counterparts. As an electron carrier, plant CB5 proteins function not only in fatty acid desaturation, hydroxylation and elongation, but also in the formation of specialized metabolites such as flavonoids, phenolic esters, and heteropolymer lignin. Furthermore, plant CB5s are found to interact with different non-catalytic proteins such as ethylene signaling regulator, cell death inhibitor, and sugar transporters, implicating their versatile regulatory roles in coordinating different metabolic and cellular processes, presumably in respect to the cellular redox status and/or carbon availability. Compared to the plentiful studies on biochemistry and cellular functions of mammalian CB5 proteins, the cellular and metabolic roles of plant CB5 proteins have received far less attention. This article summarizes the fragmentary information pertaining to the discovery of plant CB5 proteins, and discusses the conventional and peculiar functions that plant CB5s might play in different metabolic and cellular processes. Gaining comprehensive insight into the biological functions of CB5 proteins could offer effective biotechnological solutions to tailor plant chemodiversity and cellular responses to environment stimuli.
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Šrajer Gajdošik M, Kovač Peić A, Begić M, Grbčić P, Brilliant KE, Hixson DC, Josić D. Possible Role of Extracellular Vesicles in Hepatotoxicity of Acetaminophen. Int J Mol Sci 2022; 23:8870. [PMID: 36012131 PMCID: PMC9408656 DOI: 10.3390/ijms23168870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 07/29/2022] [Accepted: 08/05/2022] [Indexed: 11/16/2022] Open
Abstract
We examined proteomic profiles of rat liver extracellular vesicles (EVs) shed following treatment with a sub-toxic dose (500 mg/kg) of the pain reliever drug, acetaminophen (APAP). EVs representing the entire complement of hepatic cells were isolated after perfusion of the intact liver and analyzed with LC-MS/MS. The investigation was focused on revealing the function and cellular origin of identified EVs proteins shed by different parenchymal and non-parenchymal liver cells and their possible role in an early response of this organ to a toxic environment. Comparison of EV proteomic profiles from control and APAP-treated animals revealed significant differences. Alpha-1-macroglobulin and members of the cytochrome P450 superfamily were highly abundant proteins in EVs shed by the normal liver. In contrast, proteins like aminopeptidase N, metalloreductase STEAP4, different surface antigens like CD14 and CD45, and most members of the annexin family were detected only in EVs that were shed by livers of APAP-treated animals. In EVs from treated livers, there was almost a complete disappearance of members of the cytochrome P450 superfamily and a major decrease in other enzymes involved in the detoxification of xenobiotics. Additionally, there were proteins that predominated in non-parenchymal liver cells and in the extracellular matrix, like fibronectin, receptor-type tyrosine-protein phosphatase C, and endothelial type gp91. These differences indicate that even treatment with a sub-toxic concentration of APAP initiates dramatic perturbation in the function of this vital organ.
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Affiliation(s)
| | | | - Marija Begić
- Faculty of Medicine, University Juraj Dobrila of Pula, 52100 Pula, Croatia
| | - Petra Grbčić
- Faculty of Medicine, University Juraj Dobrila of Pula, 52100 Pula, Croatia
| | - Kate E. Brilliant
- Proteomics Core, COBRE CCRD, Rhode Island Hospital, Providence, RI 02903, USA
- Warren Alpert Medical School, Brown University, Providence, RI 02903, USA
| | - Douglas C. Hixson
- Proteomics Core, COBRE CCRD, Rhode Island Hospital, Providence, RI 02903, USA
- Warren Alpert Medical School, Brown University, Providence, RI 02903, USA
| | - Djuro Josić
- Faculty of Medicine, University Juraj Dobrila of Pula, 52100 Pula, Croatia
- Warren Alpert Medical School, Brown University, Providence, RI 02903, USA
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15
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The structure and characterization of human cytochrome P450 8B1 supports future drug design for non-alcoholic fatty liver disease and diabetes. J Biol Chem 2022; 298:102344. [PMID: 35944583 PMCID: PMC9463588 DOI: 10.1016/j.jbc.2022.102344] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/20/2022] Open
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16
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Iqbal T, Das D. Biochemical Investigation of Membrane-Bound Cytochrome b5 and the Catalytic Domain of Cytochrome b5 Reductase from Arabidopsis thaliana. Biochemistry 2022; 61:909-921. [PMID: 35475372 DOI: 10.1021/acs.biochem.2c00002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The endoplasmic reticulum (ER) membrane of plant cells contains several enzymes responsible for the biosynthesis of a diverse range of molecules essential for plant growth and holds potential for industrial applications. Many of these enzymes are dependent on electron transfer proteins to sustain their catalytic cycles. In plants, two crucial ER-bound electron transfer proteins are cytochrome b5 and cytochrome b5 reductase, which catalyze the stepwise transfer of electrons from NADH to redox enzymes such as fatty acid desaturases, cytochrome P450s, and plant aldehyde decarbonylase. Despite the high significance of plant cytochrome b5 and cytochrome b5 reductase, they have eluded detailed characterization to date. Here, we overexpressed the full-length membrane-bound cytochrome b5 isoform B from the model plant Arabidopsis thaliana in Escherichia coli, purified the protein employing detergents as well as styrene-maleic acid (SMA) copolymers, and biochemically characterized the protein. The SMA-encapsulated cytochrome b5 exhibits a discoidal shape and the characteristic features of the active heme-bound state. We also overexpressed and purified the soluble domain of cytochrome b5 reductase from A. thaliana, establishing its activity, stability, and kinetic parameters. Further, we demonstrated that the plant cytochrome b5, purified in detergents and styrene maleic acid lipid particles (SMALPs), readily accepts electrons from the cognate plant cytochrome b5 reductase and distant electron mediators such as plant NADPH-cytochrome P450 oxidoreductase and cyanobacterial NADPH-ferredoxin reductase. We also measured the kinetic parameters of cytochrome b5 reductase for cytochrome b5. Our studies are the first to report the purification and detailed biochemical characterization of the plant cytochrome b5 and cytochrome b5 reductase from the bacterial overexpression system.
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Affiliation(s)
- Tabish Iqbal
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Debasis Das
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, Karnataka 560012, India
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17
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Bart AG, Morais G, Vangala VR, Loadman PM, Pors K, Scott EE. Cytochrome P450 Binding and Bioactivation of Tumor-Targeted Duocarmycin Agents. Drug Metab Dispos 2022; 50:49-57. [PMID: 34607808 PMCID: PMC8969195 DOI: 10.1124/dmd.121.000642] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/01/2021] [Indexed: 01/03/2023] Open
Abstract
Duocarmycin natural products are promising anticancer cytotoxins but too potent for systemic use. Re-engineering of the duocarmycin scaffold has enabled the discovery of prodrugs designed for bioactivation by tissue-specific cytochrome P450 (P450) enzymes. Lead prodrugs bioactivated by both P450 isoforms CYP1A1 and CYP2W1 have shown promising results in xenograft studies; however, to fully understand the potential of these agents it is desirable to compare dual-targeting compounds with isoform-selective analogs. Such redesign requires insight into the molecular interactions with these P450 enzymes. Herein binding and metabolism of the individual stereoisomers of the indole-based duocarmycin prodrug ICT2700 and a nontoxic benzofuran analog ICT2726 were evaluated with CYP1A1 and CYP2W1, revealing differences exploitable for drug design. Although enantiomers of both compounds bound to and were metabolized by CYP1A1, the stereochemistry of the chloromethyl fragment was critical for CYP2W1 interactions. CYP2W1 differentially binds the S enantiomer of ICT2726, and its metabolite profile could potentially be used as a biomarker to identify CYP2W1 functional activity. In contrast to benzofuran-based ICT2726, CYP2W1 differentially binds the R isomer of the indole-based ICT2700 over the S stereoisomer. Thus the ICT2700 R configuration warrants further investigation as a scaffold to favor CYP2W1-selective bioactivation. Furthermore, structures of both duocarmycin S enantiomers with CYP1A1 reveal orientations correlating with nontoxic metabolites, and further drug design optimization could lead to a decrease of CYP1A1 bioactivation. Overall, distinctive structural features present in the two P450 active sites can be useful for improving P450-and thus tissue-selective-bioactivation. SIGNIFICANCE STATEMENT: Prodrug versions of the natural product duocarmycin can be metabolized by human tissue-specific cytochrome P450 (P450) enzymes 1A1 and 2W1 to form an ultrapotent cytotoxin and/or high affinity 2W1 substrates to potentially probe functional activity in situ. The current work defines the binding and metabolism by both P450 enzymes to support the design of duocarmycins selectively activated by only one human P450 enzyme.
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Affiliation(s)
- Aaron G Bart
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
| | - Goreti Morais
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
| | - Venu R Vangala
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
| | - Paul M Loadman
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
| | - Klaus Pors
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
| | - Emily E Scott
- Program in Biophysics (A.G.B., E.E.S.) and Departments of Medicinal Chemistry and Pharmacology and Biological Chemistry (E.E.S.), University of Michigan, Ann Arbor, Michigan; Institute of Cancer Therapeutics (G.M., P.M.L., K.P.), Centre for Pharmaceutical Engineering Science (V.R.V.), Faculty of Life Sciences, University of Bradford, United Kingdom
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18
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Nowrouzi B, Rios-Solis L. Redox metabolism for improving whole-cell P450-catalysed terpenoid biosynthesis. Crit Rev Biotechnol 2021; 42:1213-1237. [PMID: 34749553 DOI: 10.1080/07388551.2021.1990210] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The growing preference for producing cytochrome P450-mediated natural products in microbial systems stems from the challenging nature of the organic chemistry approaches. The P450 enzymes are redox-dependent proteins, through which they source electrons from reducing cofactors to drive their activities. Widely researched in biochemistry, most of the previous studies have extensively utilised expensive cell-free assays to reveal mechanistic insights into P450 functionalities in presence of commercial redox partners. However, in the context of microbial bioproduction, the synergic activity of P450- reductase proteins in microbial systems have not been largely investigated. This is mainly due to limited knowledge about their mutual interactions in the context of complex systems. Hence, manipulating the redox potential for natural product synthesis in microbial chassis has been limited. As the potential of redox state as crucial regulator of P450 biocatalysis has been greatly underestimated by the scientific community, in this review, we re-emphasize their pivotal role in modulating the in vivo P450 activity through affecting the product profile and yield. Particularly, we discuss the applications of widely used in vivo redox engineering methodologies for natural product synthesis to provide further suggestions for patterning on P450-based terpenoids production in microbial platforms.
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Affiliation(s)
- Behnaz Nowrouzi
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, UK.,Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, UK
| | - Leonardo Rios-Solis
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, UK.,Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, UK
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19
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Chen J, Guo Y, Huang S, Zhan H, Zhang M, Wang J, Shu Y. Integration of transcriptome and proteome reveals molecular mechanisms underlying stress responses of the cutworm, Spodoptera litura, exposed to different levels of lead (Pb). CHEMOSPHERE 2021; 283:131205. [PMID: 34147986 DOI: 10.1016/j.chemosphere.2021.131205] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 06/12/2023]
Abstract
Heavy metals are major environmental pollutants that affect organisms across different trophic levels. Herbivorous insects play an important role in the bioaccumulation, and eventually, biomagnification of these metals. Although effects of heavy metal stress on insects have been well-studied, the molecular mechanisms underlying their effects remain poorly understood. Here, we used the RNA-Seq profiling and isobaric tags for relative and absolute quantitation (iTRAQ) approaches to unravel these mechanisms in the polyphagous pest Spodoptera litura exposed to lead (Pb) at two different concentrations (12.5 and 100 mg Pb/kg; PbL and PbH, respectively). Altogether, 1392 and 1630 differentially expressed genes (DEGs) and 58, 114 differentially expressed proteins (DEPs) were identified in larvae exposed to PbL and PbH, respectively. After exposed to PbL, the main up-regulated genes clusters and proteins in S. litura larvae were associated with their metabolic processes, including carbohydrate, protein, and lipid metabolism, but the levels of cytochrome P450 associated with the pathway of xenobiotic biodegradation and metabolism were found to be decreased. In contrast, the main up-regulated genes clusters and proteins in larvae exposed to PbH were enriched in the metabolism of xenobiotic by cytochrome P450, drug metabolism-cytochrome P450, and other drug metabolism enzymes, while the down-regulated genes and proteins were found to be closely related to the lipid (lipase) and protein (serine protease, trypsin) metabolism and growth processes (cuticular protein). These findings indicate that S. litura larvae exposed to PbL could enhance food digestion and absorption to prioritize for growth rather than detoxification, whereas S. litura larvae exposed to PbH reduced food digestion and absorption and channelized the limited energy for detoxification rather than growth. These contrasting results explain the dose-dependent effects of heavy metal stress on insect life-history traits, wherein low levels of heavy metal stress induce stimulation, while high levels of heavy metal stress cause inhibition at the transcriptome and proteome levels.
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Affiliation(s)
- Jin Chen
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Yeshan Guo
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Shimin Huang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Huiru Zhan
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Meifang Zhang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Jianwu Wang
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
| | - Yinghua Shu
- Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou, 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou, 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
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Parikh SJ, Kamat S, Phillips M, Boyson SP, Yarbrough T, Davie D, Zhang Q, Glass KC, Shah MB. Insights into the Genetic Variations of Human Cytochrome P450 2C9: Structural Analysis, Characterization and Comparison. Int J Mol Sci 2021; 22:10206. [PMID: 34638547 PMCID: PMC8508694 DOI: 10.3390/ijms221910206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/10/2021] [Accepted: 09/16/2021] [Indexed: 01/22/2023] Open
Abstract
Cytochromes P450 (CYP) are one of the major xenobiotic metabolizing enzymes with increasing importance in pharmacogenetics. The CYP2C9 enzyme is responsible for the metabolism of a wide range of clinical drugs. More than sixty genetic variations have been identified in CYP2C9 with many demonstrating reduced activity compared to the wild-type (WT) enzyme. The CYP2C9*8 allele is predominantly found in persons of African ancestry and results in altered clearance of several drug substrates of CYP2C9. The X-ray crystal structure of CYP2C9*8, which represents an amino acid variation from arginine to histidine at position 150 (R150H), was solved in complex with losartan. The overall conformation of the CYP2C9*8-losartan complex was similar to the previously solved complex with wild type (WT) protein, but it differs in the occupancy of losartan. One molecule of losartan was bound in the active site and another on the surface in an identical orientation to that observed in the WT complex. However, unlike the WT structure, the losartan in the access channel was not observed in the *8 complex. Furthermore, isothermal titration calorimetry studies illustrated weaker binding of losartan to *8 compared to WT. Interestingly, the CYP2C9*8 interaction with losartan was not as weak as the CYP2C9*3 variant, which showed up to three-fold weaker average dissociation constant compared to the WT. Taken together, the structural and solution characterization yields insights into the similarities and differences of losartan binding to CYP2C9 variants and provides a useful framework for probing the role of amino acid substitution and substrate dependent activity.
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Affiliation(s)
- Sonia J. Parikh
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
| | - Sumit Kamat
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
| | - Margaret Phillips
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Samuel P. Boyson
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
| | - Thomas Yarbrough
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
| | - Dylan Davie
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
| | - Qinghai Zhang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Karen C. Glass
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Manish B. Shah
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, 106 New Scotland Avenue, Albany, NY 12208, USA; (S.J.P.); (S.K.); (M.P.); (S.P.B.); (T.Y.); (D.D.); (K.C.G.)
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21
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Nadalutti CA, Prasad R, Wilson SH. Perspectives on formaldehyde dysregulation: Mitochondrial DNA damage and repair in mammalian cells. DNA Repair (Amst) 2021; 105:103134. [PMID: 34116475 PMCID: PMC9014805 DOI: 10.1016/j.dnarep.2021.103134] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/21/2021] [Accepted: 05/09/2021] [Indexed: 12/15/2022]
Abstract
Maintaining genome stability involves coordination between different subcellular compartments providing cells with DNA repair systems that safeguard against environmental and endogenous stresses. Organisms produce the chemically reactive molecule formaldehyde as a component of one-carbon metabolism, and cells maintain systems to regulate endogenous levels of formaldehyde under physiological conditions, preventing genotoxicity, among other adverse effects. Dysregulation of formaldehyde is associated with several diseases, including cancer and neurodegenerative disorders. In the present review, we discuss the complex topic of endogenous formaldehyde metabolism and summarize advances in research on fo dysregulation, along with future research perspectives.
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Affiliation(s)
- Cristina A Nadalutti
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Rajendra Prasad
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
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22
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Kim D, Kim V, Tateishi Y, Guengerich FP. Cytochrome b 5 Binds Tightly to Several Human Cytochrome P450 Enzymes. Drug Metab Dispos 2021; 49:902-909. [PMID: 34330716 DOI: 10.1124/dmd.121.000475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/13/2021] [Indexed: 01/18/2023] Open
Abstract
Numerous studies have been reported in the past 50-plus years regarding the stimulatory role of cytochrome b 5 (b 5) in some, but not all, microsomal cytochrome P450 (P450) reactions with drugs and steroids. A missing element in most of these studies has been a sensitive and accurate measure of binding affinities of b 5 with P450s. In the course of work with P450 17A1, we developed a fluorescent derivative of a human b 5 site-directed mutant, Alexa 488-T70C-b 5, that could be used in binding assays at sub-μM concentrations. Alexa 488-T70C-b 5 bound to human P450s 1A2, 2B6, 2C8, 2C9, 2E1, 2S1, 4A11, 3A4, and 17A1, with estimated K d values ranging from 2.5 to 61 nM. Only weak binding was detected with P450 2D6, and no fluorescence attenuation was observed with P450 2A6. All of the P450s that bound b 5 have some reported activity stimulation except for P450 2S1. The affinity of P450 3A4 for b 5 was decreased somewhat by the presence of a substrate or inhibitor. The fluorescence of a P450 3A4•Alexa 488-T70C-b 5 complex was partially restored by titration with NADPH-P450 reductase (POR) (K d,apparent 89 nM), suggesting the existence of a ternary P450 3A4-b 5-POR complex, as observed previously with P450 17A1. Gel filtration evidence was also obtained for this ternary complex with P450 3A4. Overall, the results indicated that the affinity of b 5 for many P450s is very high, and that ternary P450-b 5-POR complexes are relevant in P450 3A4 reactions as opposed to a shuttle mechanism. SIGNIFICANCE STATEMENT: High-affinity binding of cytochrome b 5 (b 5) (K d < 100 nM) was observed with many drug-metabolizing cytochrome P450 (P450) enzymes. There is some correlation of binding with reported stimulation, with several exceptions. Evidence is provided for a ternary P450 3A4-b 5-NADPH-P450 reductase complex.
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Affiliation(s)
- Donghak Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Vitchan Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Yasuhiro Tateishi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
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23
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Gideon DA, Nirusimhan V, E JC, Sudarsha K, Manoj KM. Mechanism of electron transfers mediated by cytochromes c and b5 in mitochondria and endoplasmic reticulum: classical and murburn perspectives. J Biomol Struct Dyn 2021; 40:9235-9252. [PMID: 33998974 DOI: 10.1080/07391102.2021.1925154] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We explore the mechanism of electron transfers mediated by cytochrome c, a soluble protein involved in mitochondrial oxidative phosphorylation and cytochrome b5, a microsomal membrane protein acting as a redox aide in xenobiotic metabolism. We found minimal conservation in the sequence and surface amino acid residues of cytochrome c/b5 proteins among divergent species. Therefore, we question the evolutionary logic for electron transfer (ET) occurring through affinity binding via recognition of specific surface residues/topography. Also, analysis of putative protein-protein interactions in the crystal structures of these proteins and their redox partners did not point to any specific interaction logic. A comparison of the kinetic and thermodynamic constants of wildtype vs. mutants did not provide strong evidence to support the binding-based ET paradigm, but indicated support for diffusible reactive species (DRS)-mediated process. Topographically divergent cytochromes from one species have been substituted for reaction with proteins from other species, implying the involvement of non-specific interactions. We provide a viable alternative (murburn concept) to classical protein-protein binding-based long range ET mechanism. To account for the promiscuity of interactions and solvent-accessible hemes, we propose that the two proteins act as non- specific redox capacitors, mediating one-electron redox equilibriums involving DRS and unbound ions.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Daniel Andrew Gideon
- Satyamjayatu: The Science & Ethics Foundation, Palakkad District, Kerala State, India.,Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, Tamil Nadu, India
| | - Vijay Nirusimhan
- Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, Tamil Nadu, India
| | - Jesu Castin E
- Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, Tamil Nadu, India
| | - Karthik Sudarsha
- Department of Biotechnology and Bioinformatics, Bishop Heber College (Autonomous), Tiruchirappalli, Tamil Nadu, India
| | - Kelath Murali Manoj
- Satyamjayatu: The Science & Ethics Foundation, Palakkad District, Kerala State, India
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24
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Estrada DF, Kumar A, Campomizzi CS, Jay N. Crystal Structures of Drug-Metabolizing CYPs. Methods Mol Biol 2021; 2342:171-192. [PMID: 34272695 PMCID: PMC10813703 DOI: 10.1007/978-1-0716-1554-6_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The complex enzyme kinetics displayed by drug-metabolizing cytochrome P450 enzymes (CYPs) (see Chapter 9 ) can, in part, be explained by an examination of their crystallographic protein structures. Fortunately, despite low sequence similarity between different families of drug-metabolizing CYPs, there exists a high degree of structural homology within the superfamily. This similarity in the protein fold allows for a direct comparison of the structural features of CYPs that contribute toward differences in substrate binding, heterotropic and homotropic cooperativity, and genetic variability in drug metabolism. In this chapter, we first provide an overview of the nomenclature and the role of structural features that are common in all CYPs. We then apply these definitions to understand the different substrate specificities and functions in the CYP3A, CYP2C, and CYP2D families of enzymes.
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Affiliation(s)
| | - Amit Kumar
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
| | | | - Natalie Jay
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
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25
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Pochapsky TC. A dynamic understanding of cytochrome P450 structure and function through solution NMR. Curr Opin Biotechnol 2020; 69:35-42. [PMID: 33360373 DOI: 10.1016/j.copbio.2020.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022]
Abstract
Many economically important biosyntheses incorporate regiospecific and stereospecific oxidations at unactivated carbons. Such oxidations are commonly catalyzed by cytochrome P450 monooxygenases, heme-containing enzymes that activate molecular oxygen while selectively binding and orienting the substrate for reaction. Despite the plethora of P450-catalyzed reactions, the P450 fold is highly conserved, and static structures are often insufficient for characterizing conformational states that contribute to specificity. High-resolution solution nuclear magnetic resonance (NMR) offers insights into dynamic processes and conformational changes that are required of a P450 in order to attain the combination of specificity and efficiency required for these reactions.
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Affiliation(s)
- Thomas C Pochapsky
- Departments of Chemistry, Biochemistry and The Rosenstiel Institute for Basic Medical Research, Brandeis University, 415 South St., Waltham, MA 02454, USA.
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26
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Parikh SJ, Evans CM, Obi JO, Zhang Q, Maekawa K, Glass KC, Shah MB. Structure of Cytochrome P450 2C9*2 in Complex with Losartan: Insights into the Effect of Genetic Polymorphism. Mol Pharmacol 2020; 98:529-539. [PMID: 32938720 DOI: 10.1124/molpharm.120.000042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/26/2020] [Indexed: 12/21/2022] Open
Abstract
The human CYP2C9 plays a crucial role in the metabolic clearance of a wide range of clinical therapeutics. The *2 allele is a prevalent genetic variation in CYP2C9 that is found in various populations. A marked reduction of catalytic activity toward many important drug substrates has been demonstrated by CYP2C9*2, which represents an amino acid variation at position 144 from arginine to cysteine. The crystal structure of CYP2C9*2 in complex with an antihypertensive drug losartan was solved using X-ray crystallography at 3.1-Å resolution. The Arg144Cys variation in the *2 complex disrupts the hydrogen-bonding interactions that were observed between the side chain of arginine and neighboring residues in the losartan complex of CYP2C9 and the wild-type (WT) ligand-free structure. The conformation of several secondary structural elements is affected, thereby altering the binding and orientation of drug and important amino acid side chains in the distal active site cavity. The new structure revealed distinct interactions of losartan in the compact active site of CYP2C9*2 and differed in occupancy at the other binding sites previously identified in the WT-losartan complex. Furthermore, the binding studies in solution using losartan illustrated lower activity of the CYP2C9*2 compared with the WT. Together, the findings yield valuable insights into the decreased hydroxylation activity of losartan in patients carrying CYP2C9*2 allele and provide a useful framework to investigate the effect of a single-nucleotide polymorphism that leads to altered metabolism of diverse drug substrates. SIGNIFICANCE STATEMENT: The *2 allele of the human drug-metabolizing enzyme CYP2C9 is found in different populations and results in significantly reduced activity toward various drug substrates. How the CYP2C9*2 variant induces altered drug metabolism is poorly understood given that the Arg144Cys variation is located far away from the active site. This work yield insight into the effect of distal variation using multitude of techniques that include X-ray crystallography, isothermal titration calorimetry, enzymatic characterization, and computational studies.
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Affiliation(s)
- Sonia J Parikh
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Chiara M Evans
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Juliet O Obi
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Qinghai Zhang
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Keiko Maekawa
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Karen C Glass
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
| | - Manish B Shah
- Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (S.J.P., C.M.E., J.O.O., K.C.G., M.B.S.); Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California (Q.Z.); and Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts, Kodo, Kyotanabe, Kyoto, Japan (K.M.)
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27
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Deodhar M, Al Rihani SB, Arwood MJ, Darakjian L, Dow P, Turgeon J, Michaud V. Mechanisms of CYP450 Inhibition: Understanding Drug-Drug Interactions Due to Mechanism-Based Inhibition in Clinical Practice. Pharmaceutics 2020; 12:pharmaceutics12090846. [PMID: 32899642 PMCID: PMC7557591 DOI: 10.3390/pharmaceutics12090846] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 12/11/2022] Open
Abstract
In an ageing society, polypharmacy has become a major public health and economic issue. Overuse of medications, especially in patients with chronic diseases, carries major health risks. One common consequence of polypharmacy is the increased emergence of adverse drug events, mainly from drug–drug interactions. The majority of currently available drugs are metabolized by CYP450 enzymes. Interactions due to shared CYP450-mediated metabolic pathways for two or more drugs are frequent, especially through reversible or irreversible CYP450 inhibition. The magnitude of these interactions depends on several factors, including varying affinity and concentration of substrates, time delay between the administration of the drugs, and mechanisms of CYP450 inhibition. Various types of CYP450 inhibition (competitive, non-competitive, mechanism-based) have been observed clinically, and interactions of these types require a distinct clinical management strategy. This review focuses on mechanism-based inhibition, which occurs when a substrate forms a reactive intermediate, creating a stable enzyme–intermediate complex that irreversibly reduces enzyme activity. This type of inhibition can cause interactions with drugs such as omeprazole, paroxetine, macrolide antibiotics, or mirabegron. A good understanding of mechanism-based inhibition and proper clinical management is needed by clinicians when such drugs are prescribed. It is important to recognize mechanism-based inhibition since it cannot be prevented by separating the time of administration of the interacting drugs. Here, we provide a comprehensive overview of the different types of mechanism-based inhibition, along with illustrative examples of how mechanism-based inhibition might affect prescribing and clinical behaviors.
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Affiliation(s)
- Malavika Deodhar
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
| | - Sweilem B Al Rihani
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
| | - Meghan J. Arwood
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
| | - Lucy Darakjian
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
| | - Pamela Dow
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
| | - Jacques Turgeon
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montreal, QC H3C 3J7, Canada
| | - Veronique Michaud
- Tabula Rasa HealthCare Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (M.D.); (S.B.A.R.); (M.J.A.); (L.D.); (P.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montreal, QC H3C 3J7, Canada
- Correspondence: ; Tel.: +1-856-938-8697
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28
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Wróbel TM, Rogova O, Andersen KL, Yadav R, Brixius-Anderko S, Scott EE, Olsen L, Jørgensen FS, Björkling F. Discovery of Novel Non-Steroidal Cytochrome P450 17A1 Inhibitors as Potential Prostate Cancer Agents. Int J Mol Sci 2020; 21:ijms21144868. [PMID: 32660148 PMCID: PMC7402352 DOI: 10.3390/ijms21144868] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/21/2020] [Accepted: 07/07/2020] [Indexed: 12/11/2022] Open
Abstract
The current study presents the design, synthesis, and evaluation of novel cytochrome P450 17A1 (CYP17A1) ligands. CYP17A1 is a key enzyme in the steroidogenic pathway that produces androgens among other steroids, and it is implicated in prostate cancer. The obtained compounds are potent enzyme inhibitors (sub µM) with antiproliferative activity in prostate cancer cell lines. The binding mode of these compounds is also discussed.
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Affiliation(s)
- Tomasz M. Wróbel
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (O.R.); (L.O.); (F.S.J.); (F.B.)
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Medical University of Lublin, Chodźki 4a, 20093 Lublin, Poland
- Correspondence: ; Tel.: +48-814-487-273
| | - Oksana Rogova
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (O.R.); (L.O.); (F.S.J.); (F.B.)
| | - Kasper L. Andersen
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark;
| | - Rahul Yadav
- Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA; (R.Y.); (S.B.-A.); (E.E.S.)
| | - Simone Brixius-Anderko
- Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA; (R.Y.); (S.B.-A.); (E.E.S.)
| | - Emily E. Scott
- Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA; (R.Y.); (S.B.-A.); (E.E.S.)
- Department of Pharmacology, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
| | - Lars Olsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (O.R.); (L.O.); (F.S.J.); (F.B.)
- Protein Engineering, Novozymes A/S, Krogshøjvej 36, DK-2880 Bagsvaerd, Denmark
| | - Flemming Steen Jørgensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (O.R.); (L.O.); (F.S.J.); (F.B.)
| | - Fredrik Björkling
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (O.R.); (L.O.); (F.S.J.); (F.B.)
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29
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Esteves F, Campelo D, Gomes BC, Urban P, Bozonnet S, Lautier T, Rueff J, Truan G, Kranendonk M. The Role of the FMN-Domain of Human Cytochrome P450 Oxidoreductase in Its Promiscuous Interactions With Structurally Diverse Redox Partners. Front Pharmacol 2020; 11:299. [PMID: 32256365 PMCID: PMC7094780 DOI: 10.3389/fphar.2020.00299] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/28/2020] [Indexed: 12/18/2022] Open
Abstract
NADPH cytochrome P450 oxidoreductase (CPR) is the obligatory electron supplier that sustains the activity of microsomal cytochrome P450 (CYP) enzymes. The variant nature of the isoform-specific proximal interface of microsomal CYPs indicates that CPR is capable of multiple degenerated interactions with CYPs for electron transfer, through different binding mechanisms, and which are still not well-understood. Recently, we showed that CPR dynamics allows formation of open conformations that can be sampled by its structurally diverse redox partners in a CYP-isoform dependent manner. To further investigate the role of the CPR FMN-domain in effective binding of CPR to its diverse acceptors and to clarify the underlying molecular mechanisms, five different CPR-FMN-domain random mutant libraries were created. These libraries were screened for mutants with increased activity when combined with specific CYP-isoforms. Seven CPR-FMN-domain mutants were identified, supporting a gain in activity for CYP1A2 (P117H, G144C, A229T), 2A6 (P117L/L125V, G175D, H183Y), or 3A4 (N151D). Effects were evaluated using extended enzyme kinetic analysis, cytochrome b 5 competition, ionic strength effect on CYP activity, and structural analysis. Mutated residues were located either in or adjacent to several acidic amino acid stretches - formerly indicated to be involved in CPR:CYP interactions - or close to two tyrosine residues suggested to be involved in FMN binding. Several of the identified positions co-localize with mutations found in naturally occurring CPR variants that were previously shown to cause CYP-isoform-dependent effects. The mutations do not seem to significantly alter the geometry of the FMN-domain but are likely to cause very subtle alterations leading to improved interaction with a specific CYP. Overall, these data suggest that CYPs interact with CPR using an isoform specific combination of several binding motifs of the FMN-domain.
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Affiliation(s)
- Francisco Esteves
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Huma Toxicology, NOVA Medical School, Faculty of Medical Sciences, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Diana Campelo
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Huma Toxicology, NOVA Medical School, Faculty of Medical Sciences, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Bruno Costa Gomes
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Huma Toxicology, NOVA Medical School, Faculty of Medical Sciences, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Philippe Urban
- Centre National de la Recherche, Scientifique, Institut National de la Recherche Agronomique, Institut National des Sciences Appliqu es de Toulouse, Toulouse Biotechnology Institute, Universit de Toulouse, Toulouse, France
| | - Sophie Bozonnet
- Centre National de la Recherche, Scientifique, Institut National de la Recherche Agronomique, Institut National des Sciences Appliqu es de Toulouse, Toulouse Biotechnology Institute, Universit de Toulouse, Toulouse, France
| | - Thomas Lautier
- Centre National de la Recherche, Scientifique, Institut National de la Recherche Agronomique, Institut National des Sciences Appliqu es de Toulouse, Toulouse Biotechnology Institute, Universit de Toulouse, Toulouse, France
| | - José Rueff
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Huma Toxicology, NOVA Medical School, Faculty of Medical Sciences, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Gilles Truan
- Centre National de la Recherche, Scientifique, Institut National de la Recherche Agronomique, Institut National des Sciences Appliqu es de Toulouse, Toulouse Biotechnology Institute, Universit de Toulouse, Toulouse, France
| | - Michel Kranendonk
- Centre for Toxicogenomics and Human Health (ToxOmics), Genetics, Oncology and Huma Toxicology, NOVA Medical School, Faculty of Medical Sciences, Universidade NOVA de Lisboa, Lisbon, Portugal
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Thesseling FA, Hutter MC, Wiek C, Kowalski JP, Rettie AE, Girhard M. Novel insights into oxidation of fatty acids and fatty alcohols by cytochrome P450 monooxygenase CYP4B1. Arch Biochem Biophys 2020; 679:108216. [PMID: 31801692 DOI: 10.1016/j.abb.2019.108216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/26/2019] [Accepted: 11/29/2019] [Indexed: 10/25/2022]
Abstract
CYP4B1 is an enigmatic mammalian cytochrome P450 monooxygenase acting at the interface between xenobiotic and endobiotic metabolism. A prominent CYP4B1 substrate is the furan pro-toxin 4-ipomeanol (IPO). Our recent investigation on metabolism of IPO related compounds that maintain the furan functionality of IPO while replacing its alcohol group with alkyl chains of varying structure and length revealed that, in addition to cytotoxic reactive metabolite formation (resulting from furan activation) non-cytotoxic ω-hydroxylation at the alkyl chain can also occur. We hypothesized that substrate reorientations may happen in the active site of CYP4B1. These findings prompted us to re-investigate oxidation of unsaturated fatty acids and fatty alcohols with C9-C16 carbon chain length by CYP4B1. Strikingly, we found that besides the previously reported ω- and ω-1-hydroxylations, CYP4B1 is also capable of α-, β-, γ-, and δ-fatty acid hydroxylation. In contrast, fatty alcohols of the same chain length are exclusively hydroxylated at ω, ω-1, and ω-2 positions. Docking results for the corresponding CYP4B1-substrate complexes revealed that fatty acids can adopt U-shaped bonding conformations, such that carbon atoms in both arms may approach the heme-iron. Quantum chemical estimates of activation energies of the hydrogen radical abstraction by the reactive compound 1 as well as electron densities of the substrate orbitals led to the conclusion that fatty acid and fatty alcohol oxidations by CYP4B1 are kinetically controlled reactions.
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Affiliation(s)
- Florian A Thesseling
- Institute of Biochemistry, Heinrich-Heine University, 40225, Düsseldorf, Germany.
| | - Michael C Hutter
- Center for Bioinformatics, Saarland University, 66123, Saarbrücken, Germany.
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich-Heine University, 40225, Düsseldorf, Germany.
| | - John P Kowalski
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA, 98195, USA.
| | - Allan E Rettie
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA, 98195, USA.
| | - Marco Girhard
- Institute of Biochemistry, Heinrich-Heine University, 40225, Düsseldorf, Germany.
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König L, Brixius‐Anderko S, Milhim M, Tavouli‐Abbas D, Hutter MC, Hannemann F, Bernhardt R. Identification and circumvention of bottlenecks in CYP21A2‐mediated premedrol production using recombinantEscherichia coli. Biotechnol Bioeng 2019; 117:901-911. [DOI: 10.1002/bit.27246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/29/2019] [Accepted: 11/30/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Lisa König
- Department of Biochemistry Saarland University Saarbrücken Germany
| | | | - Mohammed Milhim
- Department of Biochemistry Saarland University Saarbrücken Germany
| | | | | | - Frank Hannemann
- Department of Biochemistry Saarland University Saarbrücken Germany
| | - Rita Bernhardt
- Department of Biochemistry Saarland University Saarbrücken Germany
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32
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Kumar A, Estrada DF. Specificity of the Redox Complex between Cytochrome P450 24A1 and Adrenodoxin Relies on Carbon-25 Hydroxylation of Vitamin-D Substrate. Drug Metab Dispos 2019; 47:974-982. [PMID: 31289106 DOI: 10.1124/dmd.119.087759] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/01/2019] [Indexed: 11/22/2022] Open
Abstract
Metabolic deactivation of 1,25(OH)2D3 is initiated by modification of the vitamin-D side chain, as carried out by the mitochondrial cytochrome P450 24A1 (CYP24A1). In addition to its role in vitamin-D metabolism, CYP24A1 is involved in catabolism of vitamin-D analogs, thereby reducing their efficacy. CYP24A1 function relies on electron transfer from the soluble ferredoxin protein adrenodoxin (Adx). Recent structural evidence suggests that regioselectivity of the CYP24A1 reaction may correlate with distinct modes of Adx recognition. Here we used nuclear magnetic resonance (NMR) spectroscopy to monitor the structure of 15N-labeled full-length Adx from rat while forming the complex with rat CYP24A1 in the ligand-free state or bound to either 1,25(OH)2D3 or the vitamin-D supplement 1α(OH)D3. Although both vitamin-D ligands were found to induce a reduction in overall NMR peak broadening, thereby suggesting ligand-induced disruption of the complex, a crosslinking analysis suggested that ligand does not have a significant effect on the relative association affinities of the redox complexes. However, a key finding is that, whereas the presence of primary CYP24A1 substrate was found to induce NMR peak broadening focused on the putative recognition site α-helix 3 of rat adrenodoxin, the interaction in the presence of 1α(OH)D3, which is lacking the carbon-25 hydroxyl, results in disruption of the NMR peak broadening pattern, thus indicating a ligand-induced nonspecific protein interaction. These findings provide a structural basis for the poor substrate turnover of side-chain-modified vitamin-D analogs, while also confirming that specificity of the CYP24A1-ligand interaction influences specificity of CYP24A1-Adx recognition. SIGNIFICANCE STATEMENT: Mitochondrial cytochrome P450 enzymes, such as CYP24A1 responsible for catabolizing vitamin-D and its analogs, rely on a protein-protein interaction with a ferredoxin in order to receive delivery of the electrons required for catalysis. In this study, we demonstrate that this protein interaction is influenced by the enzyme-ligand interaction that precedes it. Specifically, vitamin-D missing carbon-25 hydroxylation binds the enzyme active site with high affinity but results in a loss of P450-ferredoxin binding specificity.
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Affiliation(s)
- Amit Kumar
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo New York
| | - D Fernando Estrada
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo New York
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Abstract
![]()
Enzyme function requires that enzyme structures be dynamic. Substrate
binding, product release, and transition state stabilization typically
involve different enzyme conformers. Furthermore, in multistep enzyme-catalyzed
reactions, more than one enzyme conformation may be important for
stabilizing different transition states. While X-ray crystallography
provides the most detailed structural information of any current methodology,
X-ray crystal structures of enzymes capture only those conformations
that fit into the crystal lattice, which may or may not be relevant
to function. Solution nuclear magnetic resonance (NMR) methods can
provide an alternative approach to characterizing enzymes under nonperturbing
and controllable conditions, allowing one to identify and localize
dynamic processes that are important to function. However, many enzymes
are too large for standard approaches to making sequential resonance
assignments, a critical first step in analyzing and interpreting the
wealth of information inherent in NMR spectra. This Account
describes our long-standing NMR-based research into
structural and dynamic aspects of function in the cytochrome P450
monooxygenase superfamily. These heme-containing enzymes typically
catalyze the oxidation of unactivated C–H and C=C bonds
in a multitude of substrates, often with complete regio- and stereospecificity.
Over 600 000 genes in GenBank have been assigned to P450s,
yet all known P450 structures exhibit a highly conserved and unique
fold. This combination of functional and structural conservation with
a vast substrate clientele, each substrate having multiple possible
sites for oxidation, makes the P450s a unique target for understanding
the role of enzyme structure and dynamics in determining a particular
substrate–product combination. P450s are large by solution
NMR standards, requiring us to develop specialized approaches for
making sequential resonance assignments and interpreting the spectral
changes that occur as a function of changing conditions (e.g., oxidation
and spin state changes, ligand, substrate or effector binding). Solution
conformations are characterized by the fitting of residual dipolar
couplings (RDCs) measured for sequence-specifically assigned amide
N–H correlations to alignment tensors optimized in the course
of restrained molecular dynamics (MD) simulations. The conformational
ensembles obtained by such RDC-restrained simulations, which we call
“soft annealing”, are then tested by site-directed mutation
and spectroscopic and activity assays for relevance. These efforts
have gained us insights into cryptic conformational changes associated
with substrate and redox partner binding that were not suspected from
crystal structures, but were shown by subsequent work to be relevant
to function. Furthermore, it appears that many of these changes can
be generalized to P450s besides those that we have characterized,
providing guidance for enzyme engineering efforts. While past research
was primarily directed at the more tractable prokaryotic P450s, our
current efforts are aimed at medically relevant human enzymes, including
CYP17A1, CYP2D6, and CYP3A4.
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Abstract
Enzymes are complex biological catalysts and are critical to life. Most oxidations of chemicals are catalyzed by cytochrome P450 (P450, CYP) enzymes, which generally utilize mixed-function oxidase stoichiometry, utilizing pyridine nucleotides as electron donors: NAD(P)H + O2 + R → NAD(P)+ + RO + H2O (where R is a carbon substrate and RO is an oxidized product). The catalysis of oxidations is largely understood in the context of the heme iron-oxygen complex generally referred to as Compound I, formally FeO3+, whose basis was in peroxidase chemistry. Many X-ray crystal structures of P450s are now available (≥ 822 structures from ≥146 different P450s) and have helped in understanding catalytic specificity. In addition to hydroxylations, P450s catalyze more complex oxidations, including C-C bond formation and cleavage. Enzymes derived from P450s by directed evolution can even catalyze more unusual reactions, e.g. cyclopropanation. Current P450 questions under investigation include the potential role of the intermediate Compound 0 (formally FeIII-O2 -) in catalysis of some reactions, the roles of high- and low-spin forms of Compound I, the mechanism of desaturation, the roles of open and closed structures of P450s in catalysis, the extent of processivity in multi-step oxidations, and the role of the accessory protein cytochrome b 5. More global questions include exactly how structure drives function, prediction of catalysis, and roles of multiple protein conformations.
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Affiliation(s)
- F. Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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Campelo D, Esteves F, Brito Palma B, Costa Gomes B, Rueff J, Lautier T, Urban P, Truan G, Kranendonk M. Probing the Role of the Hinge Segment of Cytochrome P450 Oxidoreductase in the Interaction with Cytochrome P450. Int J Mol Sci 2018; 19:ijms19123914. [PMID: 30563285 PMCID: PMC6321550 DOI: 10.3390/ijms19123914] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 01/08/2023] Open
Abstract
NADPH-cytochrome P450 reductase (CPR) is the unique redox partner of microsomal cytochrome P450s (CYPs). CPR exists in a conformational equilibrium between open and closed conformations throughout its electron transfer (ET) function. Previously, we have shown that electrostatic and flexibility properties of the hinge segment of CPR are critical for ET. Three mutants of human CPR were studied (S243P, I245P and R246A) and combined with representative human drug-metabolizing CYPs (isoforms 1A2, 2A6 and 3A4). To probe the effect of these hinge mutations different experimental approaches were employed: CYP bioactivation capacity of pre-carcinogens, enzyme kinetic analysis, and effect of the ionic strength and cytochrome b5 (CYB5) on CYP activity. The hinge mutations influenced the bioactivation of pre-carcinogens, which seemed CYP isoform and substrate dependent. The deviations of Michaelis-Menten kinetic parameters uncovered tend to confirm this discrepancy, which was confirmed by CYP and hinge mutant specific salt/activity profiles. CPR/CYB5 competition experiments indicated a less important role of affinity in CPR/CYP interaction. Overall, our data suggest that the highly flexible hinge of CPR is responsible for the existence of a conformational aggregate of different open CPR conformers enabling ET-interaction with structural varied redox partners.
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Affiliation(s)
- Diana Campelo
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
| | - Francisco Esteves
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
| | - Bernardo Brito Palma
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
| | - Bruno Costa Gomes
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
| | - José Rueff
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
| | - Thomas Lautier
- LISBP, Université de Toulouse, CNRS, INRA, INSA, 31077 Toulouse CEDEX 04, France.
| | - Philippe Urban
- LISBP, Université de Toulouse, CNRS, INRA, INSA, 31077 Toulouse CEDEX 04, France.
| | - Gilles Truan
- LISBP, Université de Toulouse, CNRS, INRA, INSA, 31077 Toulouse CEDEX 04, France.
| | - Michel Kranendonk
- Center for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisbon, Portugal.
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Bart AG, Scott EE. Structures of human cytochrome P450 1A1 with bergamottin and erlotinib reveal active-site modifications for binding of diverse ligands. J Biol Chem 2018; 293:19201-19210. [PMID: 30254074 DOI: 10.1074/jbc.ra118.005588] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 09/19/2018] [Indexed: 11/06/2022] Open
Abstract
Human cytochrome P450 1A1 (CYP1A1) is an extrahepatic enzyme involved in the monooxygenation of structurally diverse compounds ranging from natural products to drugs and protoxins. Because CYP1A1 has a role in human carcinogenesis, inhibiting its activity may potentially aid in cancer chemoprevention, whereas utilizing CYP1A1's oxidative activity could help selectively activate anticancer prodrugs. Such potential therapeutic purposes require detailed knowledge of CYP1A1's interactions with potential ligands. Known CYP1A1 ligands also vary substantially in size, and it has not been apparent from a single existing CYP1A1 structure how larger, structurally diverse ligands are accommodated within the enclosed active site. Here, two new X-ray structures with the natural product furanocoumarin bergamottin (at 2.85 Å resolution) and the lung cancer drug erlotinib (3.0 Å) revealed binding orientations consistent with the formation of innocuous metabolites and of toxic metabolites, respectively. They also disclosed local changes in the roof of the active site that enlarge the active site and ultimately form a channel to the protein exterior. Although further structural modifications would be required to accommodate the largest CYP1A1 ligands, knowing which components of the active site are malleable provides powerful information for those attempting to use computational approaches to predict compound binding and substrate metabolism by this clinically relevant monooxygenase.
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Affiliation(s)
| | - Emily E Scott
- From the Program in Biophysics and .,Departments of Medicinal Chemistry and.,Pharmacology, University of Michigan, Ann Arbor, Michigan 48109
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37
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Jeffreys LN, Girvan HM, McLean KJ, Munro AW. Characterization of Cytochrome P450 Enzymes and Their Applications in Synthetic Biology. Methods Enzymol 2018; 608:189-261. [PMID: 30173763 DOI: 10.1016/bs.mie.2018.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cytochrome P450 monooxygenase enzymes (P450s) catalyze a diverse array of chemical transformations, most originating from the insertion of an oxygen atom into a substrate that binds close to the P450 heme. The oxygen is delivered by a highly reactive heme iron-oxo species (compound I) and, according to the chemical nature of the substrate and its position in the active site, the P450 can catalyze a wide range of reactions including, e.g., hydroxylation, reduction, decarboxylation, sulfoxidation, N- and O-demethylation, epoxidation, deamination, CC bond formation and breakage, nitration, and dehalogenation. In this chapter, we describe the structural, biochemical, and catalytic properties of the P450s, along with spectroscopic and analytical methods used to characterize P450 enzymes and their redox partners. Important uses of P450 enzymes are highlighted, including how various P450s have been exploited for applications in synthetic biology.
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Affiliation(s)
- Laura N Jeffreys
- Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom
| | - Hazel M Girvan
- Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom
| | - Kirsty J McLean
- Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom
| | - Andrew W Munro
- Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
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38
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Godamudunage MP, Grech AM, Scott EE. Comparison of Antifungal Azole Interactions with Adult Cytochrome P450 3A4 versus Neonatal Cytochrome P450 3A7. Drug Metab Dispos 2018; 46:1329-1337. [PMID: 29991575 DOI: 10.1124/dmd.118.082032] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/09/2018] [Indexed: 12/31/2022] Open
Abstract
Adult drug metabolism is dominated by cytochrome P450 3A4 (CYP3A4), which is often inhibited by antifungal azole drugs, resulting in potential alterations in drug metabolism and adverse drug/drug interactions. In the fetal and neonatal stages of life, the 87% identical cytochrome P450 3A7 (CYP3A7) is expressed but not CYP3A4. Azole antifungals developed for adults are also used in neonates, assuming they interact similarly with both enzymes, but systematic information is lacking. Herein a method was developed for generating recombinant purified CYP3A7. Thirteen different azoles were then evaluated for binding and inhibition of purified human CYP3A4 versus CYP3A7. All imidazole-containing azoles bound both enzymes via coordination to the heme iron and inhibited both with IC50 values ranging from 180 nM for clotrimazole to the millimolar range for imidazole itself. Across this wide range of potencies, CYP3A4 was consistently inhibited more strongly than CYP3A7, with clotrimazole being the least selective (1.5-fold) inhibitor and econazole the most selective (12-fold). Observations for 1,2,4-triazole-containing azoles were more varied. Most bound to CYP3A4 via coordination to the heme iron, but several also demonstrated evidence of a distinct binding mode at low concentrations. However, only posaconazole inhibited CYP3A4. Of the triazoles, only posaconazole inhibited CYP3A7, again less potently than CYP3A4. Spectral evidence for binding was weak or nonexistent for all triazoles. Overall, although the details of binding interactions do vary, the same azole compounds inhibit both enzymes, albeit with weaker interactions with CYP3A7 compared with CYP3A4.
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Affiliation(s)
- Malika P Godamudunage
- Departments of Medicinal Chemistry (M.P.G., A.M.G., E.E.S.) and Pharmacology (E.E.S.), University of Michigan, Ann Arbor, Michigan
| | - Anne M Grech
- Departments of Medicinal Chemistry (M.P.G., A.M.G., E.E.S.) and Pharmacology (E.E.S.), University of Michigan, Ann Arbor, Michigan
| | - Emily E Scott
- Departments of Medicinal Chemistry (M.P.G., A.M.G., E.E.S.) and Pharmacology (E.E.S.), University of Michigan, Ann Arbor, Michigan
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39
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Baranowski ES, Arlt W, Idkowiak J. Monogenic Disorders of Adrenal Steroidogenesis. Horm Res Paediatr 2018; 89:292-310. [PMID: 29874650 PMCID: PMC6067656 DOI: 10.1159/000488034] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 02/27/2018] [Indexed: 12/19/2022] Open
Abstract
Disorders of adrenal steroidogenesis comprise autosomal recessive conditions affecting steroidogenic enzymes of the adrenal cortex. Those are located within the 3 major branches of the steroidogenic machinery involved in the production of mineralocorticoids, glucocorticoids, and androgens. This mini review describes the principles of adrenal steroidogenesis, including the newly appreciated 11-oxygenated androgen pathway. This is followed by a description of pathophysiology, biochemistry, and clinical implications of steroidogenic disorders, including mutations affecting cholesterol import and steroid synthesis, the latter comprising both mutations affecting steroidogenic enzymes and co-factors required for efficient catalysis. A good understanding of adrenal steroidogenic pathways and their regulation is crucial as the basis for sound management of these disorders, which in the majority present in early childhood.
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Affiliation(s)
- Elizabeth S. Baranowski
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom,Department of Paediatric Endocrinology and Diabetes, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom
| | - Wiebke Arlt
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom,*Prof. Wiebke Arlt, Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT (UK), E-Mail
| | - Jan Idkowiak
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom,Department of Paediatric Endocrinology and Diabetes, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom
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40
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Fehl C, Vogt CD, Yadav R, Li K, Scott EE, Aubé J. Structure-Based Design of Inhibitors with Improved Selectivity for Steroidogenic Cytochrome P450 17A1 over Cytochrome P450 21A2. J Med Chem 2018; 61:4946-4960. [PMID: 29792703 PMCID: PMC6367708 DOI: 10.1021/acs.jmedchem.8b00419] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inhibition of androgen biosynthesis is clinically effective for treating androgen-responsive prostate cancer. Abiraterone is a clinical first-in-class inhibitor of cytochrome P450 17A1 (CYP17A1) required for androgen biosynthesis. However, abiraterone also causes hypertension, hypokalemia, and edema, likely due in part to off-target inhibition of another steroidogenic cytochrome P450, CYP21A2. Abiraterone analogs were designed based on structural evidence that B-ring substituents may favorably interact with polar residues in binding CYP17A1 and sterically clash with residues in the CYP21A2 active site. The best analogs increased selectivity of CYP17A1 inhibition up to 84-fold compared with 6.6-fold for abiraterone. Cocrystallization with CYP17A1 validated the intended new contacts with CYP17A1 active site residues. Docking these analogs into CYP21A2 identified steric clashes that likely underlie decreased binding and CYP21A2 inhibition. Overall, these analogs may offer a clinical advantage in the form of reduced side effects.
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Affiliation(s)
- Charlie Fehl
- Department of Medicinal Chemistry, University of
Kansas, Lawrence, Kansas, 66047, United States
| | - Caleb D. Vogt
- Division of Chemical Biology and Medicinal
Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel
Hill, Chapel Hill, North Carolina 27599, United States
| | - Rahul Yadav
- Department of Medicinal Chemistry, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Kelin Li
- Division of Chemical Biology and Medicinal
Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel
Hill, Chapel Hill, North Carolina 27599, United States
| | - Emily E. Scott
- Department of Medicinal Chemistry, University of
Michigan, Ann Arbor, Michigan 48109, United States
- Department of Pharmacology, University of Michigan,
Ann Arbor, Michigan 48109, United States
| | - Jeffrey Aubé
- Division of Chemical Biology and Medicinal
Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel
Hill, Chapel Hill, North Carolina 27599, United States
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Šrejber M, Navrátilová V, Paloncýová M, Bazgier V, Berka K, Anzenbacher P, Otyepka M. Membrane-attached mammalian cytochromes P450: An overview of the membrane's effects on structure, drug binding, and interactions with redox partners. J Inorg Biochem 2018; 183:117-136. [DOI: 10.1016/j.jinorgbio.2018.03.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/16/2018] [Accepted: 03/01/2018] [Indexed: 01/08/2023]
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Chen C, Liu J, Halpert JR, Wilderman PR. Use of Phenoxyaniline Analogues To Generate Biochemical Insights into the Interactio n of Polybrominated Diphenyl Ether with CYP2B Enzymes. Biochemistry 2018; 57:817-826. [PMID: 29215266 DOI: 10.1021/acs.biochem.7b01024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Human hepatic cytochromes P450 (CYP) are integral to xenobiotic metabolism. CYP2B6 is a major catalyst of biotransformation of environmental toxicants, including polybrominated diphenyl ethers (PBDEs). CYP2B substrates tend to contain halogen atoms, but the biochemical basis for this selectivity and for species specific determinants of metabolism has not been identified. Spectral binding titrations and inhibition studies were performed to investigate interactions of rat CYP2B1, rabbit CYP2B4, and CYP2B6 with a series of phenoxyaniline (POA) congeners that are analogues of PBDEs. For most congeners, there was a <3-fold difference between the spectral binding constants (KS) and IC50 values. In contrast, large discrepancies between these values were observed for POA and 3-chloro-4-phenoxyaniline. CYP2B1 was the enzyme most sensitive to POA congeners, so the Val-363 residue from that enzyme was introduced into CYP2B4 or CYP2B6. This substitution partially altered the protein-ligand interaction profiles to make them more similar to that of CYP2B1. Addition of cytochrome P450 oxidoreductase (POR) to titrations of CYP2B6 with POA or 2'4'5'TCPOA decreased the affinity of both ligands for the enzyme. Addition of cytochrome b5 to a recombinant enzyme system containing POR and CYP2B6 increased the POA IC50 value and decreased the 2'4'5'TCPOA IC50 value. Overall, the inconsistency between KS and IC50 values for POA versus 2'4'5'TCPOA is largely due to the effects of redox partner binding. These results provide insight into the biochemical basis of binding of diphenyl ethers to human CYP2B6 and changes in CYP2B6-mediated metabolism that are dependent on POA congener and redox partner identity.
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Affiliation(s)
- Chao Chen
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - Jingbao Liu
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - James R Halpert
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - P Ross Wilderman
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
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